Process for producing alkali metal adducts of aromatic solvent extracts of petroleum fractions, the products thereof and carbonation of the products



SOLVENT EXTRAGT Oct. 13, 1964 w ET PRocEss FoR PRoDucING ALKALI METAL ADDUcTs oF` ARDMATIC soLvENT ExTRAcTs 0F PETRDLEUM FRAcTIoNsT, THE PRODUCTS THEREDF AND cARBoNATIoN oF THE PRoDucTs Filed Dec. so. 1960 coge. Has

ACID

E. KRAMER UNREACTE OIL BY 'Rose/ir M. iA/NES A T TOR/VE Y United States Patent PROCESS FR PRGBUCENG ALKALE METAL ADDUCTS F ARGMATIC SQLVENT EX- TRACTS 0F PETROLEUM FRACTICNS, THE

Oli' THE PRUDUCTS Waiter E. Kramer, Niles, and Louis A. .loo and Robert M. Haines, Crystal Lake, Ill., assignors to rThe Pure Gil Company, Chicago, Ill., a corporation of Chio Filed Dec. 30, 1960, Ser. No. 79,661 11 Claims. r(Cl. 260-515) This invention relates to an improved process for the preparation of polyfunctional polynuclear aromatic acids from petroleum fractions rich in polynuclear `aromatics. More particularly, the invention is based on the discovery that the maximum acid yield and acid purity is obtained by dispersing the alkali metal in a petroleumderived mixture containing polynuclear aromatic constituents, combining the dispersion so formed with a reaction solvent, reacting the mixture with carbon dioxide to form salts of polycarboxylic acids, separating the salts from the reaction mixture and recovering the free acids. The process is an improvement of the process described in application Serial Number 819,932, tiled June 12, 1959, now abandoned.

In accordance with this invention, and as the features thereof, we have found that the product purity is higher, the side-reaction difficulties are eliminated if:

(l) the alkali-metal dispersions are prepared using the polynuclear aromatic feed-stock instead of an inert suspending medium,

(2) the entire quantity of polynuclear aromatic feedstock is used to make the dispersion rather than diluting the concentrates of polynuclear aromatic feed-stock and alkali metal with additional oil,

(3) the reaction-promoting solvent is added after the alkali metal-polynuclear aromatic feed-stock dispersion is prepared,

(4)'the temperature of the formation of the alkali metal-polynuclear aromatic feed-stock dispersion is regulated, and,

(5) the oil-alkali metal ratio is regulated.

By employing one or more of these features, alkali metal-to-acid conversions can be raised from a level of about 37% to as high as 65%. In terms of actual yield, this represents an increase from 3.4 to 5.2 grams of polybasic acid per gram of alkali metal reacted. Furthermore, the results obtained are much more reproducible, and the products have enhanced utility.

It becomes, therefore, a primary object of this invention to provide an improved process for the preparation of polyfunctional polynuclear aromatic acids or salts thereof from petroleum fractions rich in polynuclear aromatics.

Another object of this invention is to provide a process for the preparation of polyfunctional polynuclear aromatic acids or salts thereof from petroleum fractions incorporating one or more of the features and improvements supra.

Still another object of Vthis invention is to provide a process for the preparation of polyfunctional polynuclear aromatic acids or salts thereof from solvent extracts obtained in the solvent extraction of mineral lubricating oils and fractions thereof.

These and other objects of this invention will be described or become Iapparent as the specification proceeds.

The drawing is a flow diagram to illustrate one or more preferred embodiments of the invention.

It is known in the art that free alkali metals react with a wide variety of aromatic hydrocarbons to form the metal complex thereof. The reaction has not become Fice one 4of technical importance because of diiculties in obtaining adequate yields and the fact that the starting materials are expensive. Schlenk, in Annalen, 453, 95, reports that lithium reacts with naphthalene in ethyl ether solution to form the alkali-metal complex, or addition compound, in detectable quantities only after 8 days reaction time. The same reaction with diphenyl required 14 days. Sodium failed to give a detectable reaction with either of these hydrocarbons in a matter of months. This is attributed to the possible poisoning effect on the alkali metal of sulfur compounds present in even the best grades of such hydrocarbon starting materials. Using ammonia as the solvent is equally ineffective because of the side reactions forming sodamide.

Scott discloses in United States Patents 2,023,793; 2,019,832; and 2,054,100, and Walker shows in Patent 2,033,056 that the solvent affects the reaction. The prior art is mostly concerned with the use of extremely pure hydrocarbon starting materials, but even so, the yields are low. However, J. B. Conant and A. H. Blatt, JACS, 50, 542 (1928), describe the action of sodium-potassium alloys on various complex petroleum mixtures, such as crude oils and petroleum residua, followed by carbon dioxide to produce complex mixtures containing dibasic acids. Their yields were very l-ow, however, and their products were radically different from those of the instant invention. For example, their yields were of the order of 4.5-17 g. per liter of charge stock, Whereas the yields from our unique charge materials are of the order of Z50-400 g. per liter of charge stock. Their dibasic acid products contained n-o sulfur, nitrogen, or halogen, whereas the dibasic Kacid products of our invention contain combined sulfur to the extent of nearly one sulfur atom per molecule, on the average. Conant and Blatt were unable to obtain any solid esters from their dibasic acids,-

Whereas the products of our invention readily react with glycerine to form esters. Their products were insoluble in benzene, whereas our products are soluble. Other physical and chemical properties are also distinctively different. Most, if not all, of these profound differences arise from the great differences in the materials charged as reactants. The charge stocks of our invention are concentrated solutions of complex mixtures of polynuclear aromatic compounds and aromatic compounds containing combined sulfur, exemplified by `aromatic oils obtained as extracts in the refining of lubricating oil fractions of petroleum by means of solvents selective for aromatics and/or sulfur compounds. Such materials are entirely different from the dilute, non-sulfur-containingmaterials of Conant and Blatt, fand the properties and yields of the products of our invention are, therefore, unexpected and unique. f In accordance with the instant invention, we have found that, contrary to the prior art, t-he reaction between the alkali metal and the aromatic compound occurs without the `presence of a suitable active ether or reaction-prometing solvent. It was observed in preparing the alkalimetal dispersions in the polynuclear aromatic feed stock that a sharp temperature rise always occurs when the alkali-metal dispersions were prepared in the absence of a ydiluent such as xylene, toluene or white oil. The possibility that this temperature rise was due to the water and naphthenic acids in the feed stock was refuted by experiments showing that their removal had no effect.

The process of this invention comprises the preparation of a dispersion of alkali metalin the starting material or source of complex polynuclear aromatic and/ or alkyl aromatic hydrocarbons, later to be identified, in a dispersion zone equipped with -means for violently agitating the mixture. During the preparation of the dispersion, sucient heat is applied to bring the temperature to about 130 to 190 C. The dispersion is next mixed with a selected reaction solvent, and the temperature is allowed to subside to about to 40 C. during the addition of the reaction solvent. The solvent-adduct mixture is transferred to a cooling zone, maintained at a temperature of about 75 to -5 C., and is then passed to a carbonation reactor where carbon dioxide in either solid or gaseous form is introduced. The carbonated mixture is then passed to a flash zone where the temperature is allowed to reach ambient conditions to release excess carbon dioxide. The reaction solvent is removed by vacuum fiashing to produce a solid residue comprising unreacted alkali metal and aromatic hydrocarbon in combination with alkali metal and aromatic hydrocarbon in combination with alkali-metal salts of dicarboxylic, polynuclear, complex aromatic acids and small amounts of by-product.

For some purposes, the product may be used in this crude form if the free alkali metal is removed. Further puriiication and recovery, including unreacted alkali metal, pure acid salts, and unreacted aromatic hydrocarbons are warranted both for economic reasons and to form products which are useful to form derivatives such as esters, polyesters, polyamides, etc., qualifying as resins, plastics, extenders, and the like. For this purpose, the reaction mixture or residue is taken up in a suitable solvent and the excess alkali metal is destroyed by the addition of water or through other processes known in the art. Where the water technique is used, the solution of residue is transferred to a recovery vessel, and water is slowly added. This reaction evolves hydrogen which may be recovered. The unreacted alkali metal also may be separated rnechanically by centrifuging or filtering, and recycled in the reaction.

The solution of product residue, free of unreacted alkali metal, is mixed with a sufficient quantity of acid to reduce the pH to a value of about 7-9, with or without the addition of water and more solvent, depending on the consistency of the solution. Acidication at this point has been found to prevent emulsication dilficulties in subsequent processing. Any hydrogen suliide that is liberated during the acidification is separated and withdrawn. The foregoing steps of the process constitute the main features of this invention. The subsequent product separation and purification steps are described to complete the general disclosure of the process, and alternative purification processes may be used.

The addition of solvent at this point results in the for mation of a lower aqueous phase and an upper solvent phase. The upper phase contains primarily unreacted oil, and some by-products. The lower phase contains primarily the desired polybasic acid salts of this invention. The upper solvent phase is water-washed to form a second aqueous extract phase and a second solvent phase. The lower aqueous phase is washed with a solvent to form a second (lower) aqueous phase containing polybasic aromatic acid salts, and a second (upper) solvent phase.

The second solvent phases from these steps are combined and passed to a contact vessel Where additional Water is added to extract any remaining water-soluble salts. The raffinate or solvent phase is distilled to sepa-v rate the solvent for 4recycle and produce a bottoms comprising unreacted aromatics.

The lower aqueous phases from the foregoing water- Washing steps are combined, additional solvent is added when necessary, and the mixture is acidiiied. This operation results in the release of considerable amounts of car- 1bon dioxide, which is recycled in the process, and a liquid mixture of products. The product layer is contacted further with solvent to cause the separation of a solvent phase from any remaining water along with some of the polybasic acids. The Water phase is sent to a final wash tower where additional solvent is added to form a water phase which may be discarded and an extract phase, containing any polybasic acids, which is combined with the aforementioned solvent phase for distillation to recover the solvent as overhead and the desired polybasic acids as bottoms.

To demonstrate the features of this invention, the results of a number of experiments are shown wherein the effects of dispersion temperatures, aromatic hydrocarbon/ Valkali metal ratios, reaction solvent/ aromatic hydrocarbon ratios, time and temperature of adduct formation, carbonation temperatures, and Dry-Ice `adduct formation or instantaneous carbonation are evaluated in relation to the yield, acid number of the product, and percent of aromatic hydrocarbon reacted.

The initial contact of the alkali metal with the hydrocarbon to be reacted is vunimportant according to the prior art. However, in applying the reaction to complex polynuclear aromatic hydrocarbons, to which this invention is particularly directed, the discovery was made that the alkali metal reacted with the aromatic hydrocarbon during the formation of the dispersion.

In order to demonstrate the invention, the results of a large number of experiments will be summarized to show the general effects of the process variables. The preparation of the alkali metal-aromatic hydrocarbon dispersion, which was found to be an essential step of the process, and factors aifecting this phase of the reaction is first explained.

lt was first established that simple, fused-ring aromatic hydrocarbons such as nap'nthalene, anthracene, and a commercial synthetic aromatic react directly with an alkali metal but do not yield polycarboxylic acids in the absence of a suitable solvent. In the case of anthracene, dispersions prepared by direct mixing showed more sodium reacting than in dispersions prepared by addition of the aromatic hydrocarbons to a dispersion of the sodium in an inert solvent, such as xylene. 9,10-dihydroantlrracene was isolated after decomposition with isopropanol. The antbracene-sodium mixtures were darkblue whereas naphthalene produced no noticeable color change. Direct dispersions of Solvent Extract No. 44, the characteristics of which are shown in Table VH, in

a l5() g. to 17.5 g. ratio of solvent extract to alkali metal,

showed between 28% and 34% of the sodium reacting.

Using three different-solvent extracts and direct addition of sodium tothe complex aromatic hydrocarbon, the effect of dispersion temperature upon the yield of extract dibasic acids is shown by the following results.

TABLE I Eyect of Dzsperszon Temperature Temp. of Complex Aromatic Disper- Acid Acid Run No. Hydrocarbon sion For- Yield No. of

mation Product The acid yields in Table I are in terms of the grams of acids produced per gram of sodium reacted. In order to study the effect of time of dispersion formation on the reaction, a dispersion of solvent extract No. 44 at a 12:1 oil/Na ratio was prepared ata temperature of 165 C. When the temperature reached 165 C., the 1ispersion was agitated by starting the stirrer, and agitation was continued for definite lengths of time while the temperature was held constant. The dispersions were rapidly cooled and processed to yield the dibasic acids with the following results:

TABLE II Effect of Time of Dispersion on Acid Yield Run No. Time of Dis- Yield ofAcid Acid No. of

persion (min.) Product From the foregoing results, it is seen that with the complex type of feed hydrocarbon at 165 C. the best yield is obtained at a dispersion time of about 2-8 minutes and preferably 4-5 minutes. The yield of acid is expressed in grams of acid per gram of sodium reacted.

Earlier preliminary work showed that the oil/ alkalimetal ratio affected the reaction and products. Using solvent extract No. 44, the yields, acid numbers of the product, and the percent of oil reacted were determined at diierent oil/ alkali metal ratios, using sodium to illustrate the alkali metal. Table lll shows the results.

TABLE Ill Eect of Aromatic HC/Alkali Metal Ratio on Yield, Percent Aromatic HC Reacted, and Acid No. of Product Grams of acid per g. oi sodium reacted.

Examination of runs 27-31 in Table III reveals that as the sodium content decreased, the yield of dibasic acids per gram of reacted sodium increased, but the quantity of acid (yield) per gram of aromatic hydrocarbon diminished with sodium content. Also, the acid number of the product diminished as the oil/sodium ratio increased. It was surmised that the monobasic naphthenic acids present in the solvent extract starting material were preferentially reacting with the sodium and concentrating in the product, producing the diminishing acid numbers. To determine if this was true, runs 32-35 were made using hydrogenated solvent extract No. 44. Hydrogenation of this extract reduced the original Neut. No. from 10.7 to 1.5. *rom runs 32-35 it is seen that this treatment, removal of most of the naphthenic acids, resulted in less oilreacting, producing somewhat lower yields of polybasic acids but giving products having higher acid numbers. As the aromatic HC/ sodium ratio changed from 9:1 to 20: 1, the acid numbers of the products from the untreated solvent extract decreased 29%, While the acid number of the products from the hydrogenated solvent extract decreased only 10%. The presence of naphthenic acids in the products is undesirable if the dibasic acids are to be used for the preparation of certain resins. The bromine numbers of the acid products were unaffected by all of these changes, varying from 18 to 23 which is within the established range of 18 to 26 for dibasic acids.

The process of this invention has as one feature the discovery that the presence of the active ether or reaction solvent of the prior art is not necessary to the formation of the alkali-metal adduct in the rst stages 6 of the reaction, and any' solvent is best incorporated after dispersion of the alkali metal in the aromatic source material. The term active ether is used in the prior art to denote such solvents as dimethyl ether and dimethyl glycol ether which were first found -to inuence the reaction. Since that time, other solvents such as tetrahydrofuran, simple methyl ethers and acetals or formaldehyde have been found to be effective, resulting in the application of the term reaction solvent. In general, such reaction solvents must not adversely affect dibasic acid yields, should be unreactive with the alkali metal, inexpensive, easily handled, and easily dried to less than 0.2% of water. An evaluation of known reaction solvents, each of which had been treated in the same manner, i.e., dried using a molecular sieve and treated with lithium aluminum hydride, except for dimethylformamide which was fractionally distilled, as to their effect on dibasic-acid yield showed that tetrahydrofuran gave a yield of 5.7 g. of dibasic acids per g. of sodium reacted, methylal 5.4 g., dimethyl glycol ether 4.2 g., trimethoxyethoxypropane 2.6 g., and dioxane, dimethylformamide, diethyl ether `and tetraethoxypropane less than 0.5 g. of acids/ g. sodium reacted. The following Table IV shows the effect of the solvent/aromatic-hydrocarbon ratio on the yield and acid number of product. These experiments were conducted under optimum conditions held constant for the series of runs, i.e., in runs 36-47 fixed amounts of sodium and hydrogenated solvent extract No. 44 were combined with different quantities of solvent and cooled to 70 C., carbonated, and the resulting acids isolated.

TABLE IV Solvent] Acid No. Run No Solvent Aromatic, Yield of HC ratio Product From Table 1V it is seen that the yields and acid numbers of the products varied not only with the kind of solvent but also with the amount of solvent used. There was a maximum yield at a certain solvent/ adduct ratio for each solvent used. Tetrahydrofuran and methylal gave maximum yields at solvent/adduct ratios of 6/1 While dimethyl glycol ether Worked best at 4.5/1. The influence on acid number of product is also shown.

In further evaluating the reaction, various factors were found to afect the formation of dibasic acids from the alkali-metal adduct solutions. The prior art procedure of carbonating the adduct in solution as it was formed is satisfactory for the production of naphthalenedicarboxylic acids. This technique was found to be unsatisfactory for the complex aromatic dibasic acids of this invention. It is known that when gaseous carbon dioxide is bubbled through an ether solution of phenyllithium, there is formed benzophenone rather than lithium benzoate. The latter compound is only formed in good yield when the solution of adduct is either poured directly onto a large excess of carbon dioxide, or sprayed into a carbon dioxide atmosphere. Gaseous carbonation usually gives poor yields under these conditions. A series of experiments were devised to determine the effect of time, temperature, and carbonation procedure on dibasic acid yield. These are reported in Table V.

7 TABLE v Eject of Time, Temperature, and Carbonation Procedure on Yield of Dibasic Acids A. GASEOUS CARBONATION 1 Yield is expressed in grams of acid per gram 0l sodium reacted.

2 Acid No. is expressed in mg. KOI-I per g. of aliquot.

In conducting the experiments of Table V, a series of adduct solutions using sodium and solvent extract No. 44, followed by the addition of tetrahydrofuran, were prepared and cooled to diiferent temperatures. Under part A of the table, gaseous C02 was added until a sharp change in color signaled completion of the reaction. Runs 48, 49, and 50 show that the yields increased slightly as the temperature decreased from 20 C. to 70 C. In runs 5l-53 of part B., the adduct solutions were poured onto Dry Ice after having been cooled to 70 C. The Dry ice was allowed to remain in contact with the solution for varying lengths of time before it was removed. Under these conditions, the yields remained substantially constant and were better than the yields obtained with gaseous carbonation. In part C the adduct solutions were prepared at room temperature and then cooled to the temperatures indicated. Aliquote of 300 ml. were withdrawn periodically and poured onto Dry Ice. No attempt was made to isolate the acids from the unreacted solvent extract. The oil-acid mixture, after work-up, was weighed and titrated with potassium hydroxide. The acid number of the mixture was proportional to the acid produced in the reaction. Runs 54 to 63 show that a 25-minute delay after addition of the tetrahydrofuran and cooling to the desired temperature, followed by instantaneous carbonation, gave a maximum yield of acid at each temperature selected. As the temperature decreased, the yield decreased, but the time delay for addition of the reaction solvent was independent of temperature. While the runs at 70 C. gave better yields than those at 20 C., there was only a 10% drop in yield at the higher temperature.

The process of the invention is illustrated by reference to the drawing wherein the mixing vessel l0 is supplied with solvent extract from line 12 and alkali metal, i.e., sodium, from line 14. Vessel l0 is fitted with means (not shown) to convey and maintain therein an inert atmosphere, such as nitrogen. Contact of the sodium and solvent extract, with mixing, in vessel l0 is conducted for about 3-10 minutes. The adduct formed in vessel l0 passes through line 16 into vessel l, and there is treated with reaction solvent introduced through line 20. Vessel 18 is maintained at a temperature of about 20 C.

From vessel l the adduct solution, which now is highly colored, is transferred through line 22 to Chiller-soaker vessel 24 wherein the adduct solution is maintained at a temperature of :about 25 C. for 20 minutes or more. The chilled adduct solution is transferred from chillersoaker 24 through line 26 into carbonation reactor 28. In reaction 2S the adduct solution is contacted with lumpforrn Dry Ice which is present in excess over the stoichiometric amount necessary to completely carbonate the adduct and form the alkali-metal salt of the di-, and/or polycarboxylic acids. The conditions in carbonation reactor 28 are maintained so that instantaneous carbonation takes place.

From carbonation reactor 28, the mixture is transferred through line 30 to ash zone 32, where the mixture is warmed to room temperature, releasing excess carbon dioxide which is withdrawn through line 34. The carbon dioxide-free solution is then transferred through line 35 to vacuum vessel 36 from which the solvent is withdrawn through line 38. This results in the production of a solid residue consisting of any unreacted alkali metal and oil, in combination with alkali-metal salts of the diand polycarboxylic, polynuclear aromatic acids and small amounts of by-products. This residue is transferred through line 39 to mixing vessel 40 wherein ether or other solvent is introduced through line 42. After solution has been accomplished, the solution is transferred through line 44 to alkali metal-recovery vessel 46.

In vessel 46 water may be slowly added to the solvent solution to react with the free alkali metal. This results in the evolution of hydrogen which is withdrawn through line 48. An alternative procedure would be to recover the unreacted solid alkali metal by filtering or by centrifuging.

The resulting solution of salts is transferred through line 50 wherein it is combined with a sucient quantity of a mineral acid introduced at line 5l to reduce the pH of the solution to about 8,0. Additional water is introduced, as required, through line S2, and additional ether, if necessary, is introduced through line 54, and the mixture is passed to separating vessel 56. It has been found that by reducing the pH of the solution to a value of about 8.0 with mineral acid, the formation of emulsions in separating vessel 55 is prevented. Small amounts of hydrogen sulfide formed during these latter treatments are liberated and withdrawn by means of line 57.

Within separating vessel 56 a phase separation takes place. The upper ether phase is drawn olf through line 58 to wash tower 60 where it is contacted with additional water introduced through line 62. This treatment results in -a formation of additional aqueous phases which are allowed to separate. The washed ether phase is withdrawn through line 63, and the water phase is withdrawn through line 64. Returning to separating vessel 55, the water phase separated therein is transferred through line 66 to wash vessel 68 where it is contacted with the solvent, that is, ether, introduced through line 70. This results in the formation of two phases which are allowed to separate. The upper ether phase in wash vessel 63 is passed through line 72, and the lower water phase is withdrawn through line 73.

The ether phase from Wash tower 60 following through line 63, and the ether phase from wash vessel 68 following through line 72 are combined in line 7d and passed into contact vessel 76 where they are contacted with acid introduced through line 78. This treatment with acid converts any remaining water-soluble salts to the free acids. The resulting mixture is transferred through line S0 to water-Wash tower 82, wherein it is contacted with water entering through line S4. Any dissolved residual acids are taken up in the water and withdrawn through line for disposal. The washed ether phase from waterwash tower S2 is transferred through line S8 to distillation tower 9i? from which ether is taken as overhead through 9 line 92, and unreacted oil is withdrawn through line 94 as one of the products of the process.

The water phase from wash tower 60 tiowing through line 64, and the water phase from wash vessel 68 flowing sodium salts of the dibasic acids, and by-products of the reaction. The reactor is connected to a gas meter, and dry ether is added. Water is slowly introduced to destroy the excess sodium, and the volume of evolved hythrough line 73 are combined in line 96. Additional ether 5 drogen is measured. The amount of unreacted sodium solvent, as required, is added through line 97. The combiis calculated from the volume of liberated hydrogen. nation mixture flows to acidification vessel 98, where After the excess sodium is destroyed, additional water it is contacted with acid introduced through line 100. A and ether are added to the reactor-disperser, and two preferred acid for this treatment is hydrochloric acid. clear layers form. The ethereal solution containing the The reaction or acidification taking place in vessel 98 10 residual oil is separated, and the two layers are washed results in the evolution of large amounts of carbon dioxwith the opposite solvents. The combined ether fracide, same being withdrawn through line 162. After the tions are washed, and concentrated. The amount of uncompletion of the liberation of carbon dioxide, the rereacted oil is determined. The water solution is acidified sulting liquid mixture is withdrawn through line 194 to with a mineral acid, such as hydrochloric acid, to preether wash-tower 166 where it is contacted with ether l5 cipitate the dibasic acid products, which step causes the introduced through line 108. This treatment results in evolution of large quantities of carbon dioxide and some awater phase being separated which is withdrawn through hydrogen sulfide. Ether is added to dissolve the free line 119 to a second wash-tower 112. 1n tower 112 the acids, and the aqueous layer is extracted several times water phase is contacted with more ether introduced with ether. The water layer is discarded, and the comthrough line 114. The resulting acid-free water phase bined etherlayer is concentrated to obtain the product is withdrawn through line 116 and discarded. dibasic acids.

The ether phases from vessels 106 and 112 flowing Table VI gives the results of representative runs in through lines 11S and 120 respectively are combined in pilot-scale production.

TABLE V1 Results of Representative Runs in Pilot Scale Production of Dibasfc Acids Acid Properties Sodium Extract Extract Acid Extract Used Charged Charged Recovered Obtained (Grams) (Grams) (Grams) (Grams) Yield, g. Percent Bromine Percent Acid Acid/g. Na Number Unsaponi- Number Charged fiable 1, 482 8, 892 6, 611 2, 729 1. S 1. 9 20 4. 4 304 1, 462 8, 172 5, 639 2, 634 1.8 1. 8 19 3. 1 289 1, 362 8, 172 5, 392 2, 452 1.8 1. 9 17 3. 2 271 683 6, 151 4, 205 1, 711 2. 5 2. 5 20 6. 0 244 1, 283 7, 698 5, 426 2, 814 2. 2 2. 6 19 6. 1 272 o 556 8, 100 5, 720 2, 330 2 5.0 2. 2 20 5. 7 232 Hydrogenated Solvent Extract No. 686 6, 181 3, 781 2,143 3A 1 2.0 19 7.0 256 Hydrogenated Solvent Extract No. 43.. 666 5, 998 4, 619 1, 619 2. 4 3.2 22 6. 4 242 Hydrogenated Solvent Extract No. 411-. 454 5, 448 4, 438 888 2. 3 3. 2 184 Hydrogenated Solvent Extract N0. 431.. 454 5, 448 4, 260 1, 181 2.6 169 Hydrogenated Solvent Extract N o. 441-. 681 6, 129 3, 601 2, 174 3. 2 2. 4 105 l Unsatisfactory runs. 2 Value not reproduced. line 122 and passed to distillation tower 124. Sufficient heat is applied in tower 124 to free the product of any solvent. In this process the solvent, ether, is withdrawn as overhead in line 126. To avoid decomposition of the product, a vacuum is applied to tower 124. The finished polybasic acids of this invention are withdrawn from tower 124 through line 128.

The process as illustrated by the foregoing description may be modified to a batch operation. Using hydrogenated solvent extract No. 44, having a neutralization number of 0.96, as the feed, the following example illustrates not only the technique of the invention but also other subsidiary determinations:

EXAMPLE I Initially, 150 grams of said solvent extract and 12.5 g. of sodium are charged to a dispersion zone and heated to 160 C. under a nitrogen atmosphere. When the mixture has reached 160 C., agitation by means of a stirrer is begun and the formation ofthe dispersion commences. After about 4 minutes of agitation, the stirrer is stopped, and the dispersi-on zone is cooled to 20 C. Nine hundred ml. of anhydrous tetrahydrofuran or methylal is then added, and the mixture is again stirred to effect solution. The solution is rapidly cooled to -25 C. and maintained at that temperature for about minutes. The reaction mixture is next instantaneously carbonated by pouring it onto `a large quantity of Dry Ice. The Dry Abon from synthetic or natural sources.

Ice mixture is allowed to warm to room temperature, and I when the excess CO2 has evaporated, the mixture is concentrated under a vacuum leaving a solid residue consisting of unreacted sodium unreacted solvent extract,

The starting material for the reaction may be any cornplex polynuclear, and/ or heterocyclic aromatic hydrocar- A preferred and unique source of aromatic starting material comprises petroleum fractions rich in complex polynuclear aromatic hydrocarbons, not only because the diabasic or polybasic acid products therefrom have unique properties, but also the techniques outlined herein are particularly adapted to processing these more complex and resistant source materials. illustrating the preferred and novel starting materials is the class known as solvent extracts from the manufacture of mineral lubricating oils, which solvent extracts are rich in complex, polynuclear, aryl, alkaryl, condensed ring and heterocyclic nuclei forming the organic portion of the dibasic or polybasic carboxylic acids of this invention. Solvent extracts from the manufacture of bright stock and neutral lubricating oils are particular examples of such fractions rich in complex aromatic cornpounds obtained as by-products from the solvent refining of mineral oils.

For example, a preferred source of the above-defined complex hydrocarbons comprises the extracts obtained in solvent refining mineral oils, particularly lubricating oil fractions. These extracts, hereinafter referred to as solvent extracts, are obtained as the extract or solvent phase when lubricating oils are refined by treatment with a selective solvent having an affinity for aromatic and sulfur compounds. The complex hydrocarbons removed by this refining treatment often contain appreciable amounts of combined sulfur, nitrogen and oxygen. These complex hydrocarbons contain a predominance of polyl1 nuclear rings oi' aromatic structure, and of condensed configurations having or containing hydrocarbon substituent groups attached thereto as side chains. These starting materials are of a generally viscous nature, have 12 ity SUS at 210 F. of 1249, lash 585 F., iire 650 F., CR. of 13.9 weight percent, and may be black in color. The deasphalted oil may have an API gravity of 21.5 to 21.8, viscosity SUS at 210 F. of 165-175, NPA

low viscosity indices, low resistance to oxidation, and color 6-7, iiash 575 F., fire 650 F., and CR. of 1.7-2.0. are consideredto be deleterious in lubricating oils. Here- The deasphalted oil and various lubricating oil distillates tofore, these aromatic extracts have been regarded as from the reduced crude are subjected to solvent extracwaste products, and because they are exceedingly complition for the separation of non-aromatic from aromatic cated mixtures of complex compounds, including various constituents prior to use. The refined oil or ramnate sulfur, oxygen, and nitrogen-containing compounds, 10 from the extraction processes is used per se, or as blendthey have not been used successfully in preparing petroing stock, for lubricating oils, and the solvent extract, chemicals or as sources of hydrocarbon reactants or' startpredominating in complex aromatic constituents, is dising materials. tinctively useful in accordance with this invention.

The starting materials used are adequately described For example, a crude oil from an East Texas held, with as those aromatic materials separated from mineral lu- 15 an API gravity of 33.1, was topped to remove such light bricating oils and their fractions (i.e., those aromatics fractions as gasoline, naphtha, lrerosine, and a light lubri obtained in the manufacture and refining of neutral oils eating distillate. The vacuum residue was a reduced and bright stocks during treatment with a selective solcrude, having a viscosity of 1251 SUS at 210 F., 2.2

ent designed to extract the predominantly aromatic mapercent sulfur, and an API gravity of 12.6. After proterials from the paraflnic materials). Solvent extracts pane-deasphalting, the oil had a viscosity of 174 SUS resulting from the treatment of mineral lubricating oils at 210 F., and an API gravity of 21.7. This deasphalted for the purpose of separating non-aromatic hydrocarbons oil was treated with phenol to produce a ranate from (the raiiinate and nished oil) from the aromatic hydrowhich an aviation lubricating oil could be prepared. The earbons (the extract Vand Waste product) may be used oil extracted by phenol treatment, after removal of and are preferred yas starting materials. phenol, is ready for use as the starting material in ac- Since the general process of reiining mineral lubricat- Cordan With this inventioning oils in which solvent extracts are obtained is Well Solvents other than phenol may be used to obtain the known, it is only necessary for present purposes to deextraction product used in accordance with this invenscribe a typical procedure for obtaining same and give tion, for example, liquid sulfur dioxide, nitrobenzene, some examples by way of illustration. Chlorex, chlorophenol, trichloroethylene, cresylic acid,

In a typical operation, desalted crude oil is irst charged pyridine, furfural, or the Duo-Sol solution (comprising to a distillation unit where straight-run gasoline, two liquid propane and cresol) may be used. When using grades of naphtha, kerosine, and virgin distillate are phenol, it is possible to vary the characteristics of the extaken olf, leaving a reduced crude residue. The reduced tract and ratiinate products considerably by adjustment crude is continuously charged to a vacuum distillation of the amount of water present. A raiiinate of relatively unit where three lubricating oil distillates are taken off as low viscosity index can be obtained by using a water side streams, a light distillate is taken oit as overhead, solution or" phenol during the extraction, and a railinate and a residuuin is Withdrawn from the bottom of the of high viscosity index can be obtained by using anhytower. The residiuum is charged to a propane-deasphaltdrous phenol. Following are the physical charactenistics ing unit wherein propane dissolves the desirable lubricatof typical extract products, from lubricating oil stocks ing oil constituents and leaves the `asphaltic materials. derived from various crude oils and other source hydro- A typical vacuum residuum charge to the propane-decarbon materials, which may be used in accordance with asphalting unit may have an API gravity of 12.9, viscosthis invention.

TABLE VII A Sources and Physical Characteristics of Solvent Extracts Ext, API Sp. Gr. Vis/ Vis/ Vis/ F. F. Iodine Per- Per- No. Crude Source Solvent Grav. @10 F. 100 F. 130 F. 210 F. V.I. Pour Flash Fire No. cent cent (Wijs) CLR. Sulfur Extract No. 41 was obtained in the production ot 85 Vis neutral, had an average molecular weight of 300, and contained 76.8% aromatics (by the silica gel procedure).

Extract No. 42 was obtained in the production of 150 Vis Bright Stock, had an average molecular Weight of 590, contained 86% aromatics, 14% saturates, 86,2% carbon, 11.4% hydrogen, and averaged 3.3 aromatic rings per aromatic molecule.

Extract No. 43 was obtained in the production of 170 Vis neutral, had an average molecular Weight of 340, contained 87.0% aromatics, 13% satruates, 86.4% carbon, 10.7% hydrogen, and averaged 2.7 aromatic rings per aromatic molecule.

Extract N o. 44 was obtained in the production of 200 Vis neutral, had an av Extract No. 45 was obtained in the production of 160 Vis Bright Stock,

orage molecular weight 01'340, contained 87% aromatics and 13% saturates. contained 92% aromatics and 8% saturates.

i3 The solvent extracts from lubricaing oils used as starting materials for this invention have the following general properties and characteristics:

TABLE VIII Characteristic: Range of value Gravity, A.P.I. 8.0-l5.0 Gravity, Sp., 380/15.5 C. 09550-1000 Viscosity SUS 100 F. (ext.) 350-25,000 Viscosity SUS 130 F. 140-19,000 Viscosity SUS 210 F 200-1500 Viscosity index 101--1-39 Pourpoint (max.) +35-10O Color NPA +2-5D Molecular weight, average (above 300) 320-750 Boiling point (initial) F. 300-1000 Boiling point (end) F. 400-1200 Sul-fur, percent wt. 1.9-4.5 Sulfur compounds percent wt. 20-50 Aromatics and thio compounds 50-90 Thio compounds 14-40 Neutral aromatic hydrocarbons 40-51 Av. No. of rings/mean arom, mol. 1.7-3.5 H/C wt. ratio 0.116-0.136 H/C atom ratio, whole sample 1.3834622 H/C atom ratio, aromatic portion 1289-1500 Nearest empirical forrnula H2ZH30-C44H66 The specific vgravities of the extracts in general increase with increase in the viscosity of the raffinate at a constant viscosity index. Stated otherwise, the specic gravi- Vties of these extracts increase with decrease in viscosity index of the rafnate at a constant viscosity. For the production of 100i5 VI neutral oils, the viscosities of the extracts increase with increase in stated viscosities of the neutral oils (raiiinates). The pour points of extracts are high and are affected by changes in the depth of extraction. The sulfur contents are also affected by the depth of extraction. The solvent extracts are characterized yby containing aromatic and heterocyclic compounds in the range of 75-98%, the remainder being principally saturates, or material behaving as saturates, together with a minor proportion of up to about 7% of organic acids. The organic acids present are not susceptible to extraction by the use of Iaqueous strong caustic because of the 4solubility of the alkali metal salts of the acids in the oil. Little or no asphaltic material is present in solvent extracts and they contain essentially no materials volatile at room temperature.

The complexity of the types of compounds present, as based on .these analyses, is illustrated by the following table:

TABLE IX Estimated Chemical Composition of Solvent Extracts Nos. 19, 21, 43 and 44 of Table VII Type .of compound; Approx. percent in the extract Substituted anthracenes 5.0 Tetranuclear aromatics- Substituted chrysenes 00.5

Substituted benzphenanthrenes 0.2

Substituted pyrenes 0.2 Pentanuclear aromatics- Perylene 0.01 Sulfur compounds 1, oxygen compounds etc. 16.5

1Main1y heteroeyclic compounds. The average mol. wt. of Extracts 19 and 21 is 340, and that of Extract 20 is 590.

Portions of the reactive aromatic constituents in solvent extracts may be isolated therefrom, or from other 14 sources, to be used as starting materials for reaction in accordance with this invention. For example, solvent extracts may be distilled and selected fractions thereof used as the starting materials. The content of reactive, complex, polynuclear, aromatic compounds and heterocyclic present in solvent extracts, as illustrating the preferred source material, may vary depending on the type of solvent, the extraction process applied, and the mineral oil treated, although the general types `of compounds present in the extract are not so varied. Extracts containing trom about 30% to 90% of polynuclear aromat# ics and heterocyclics of aromatic nature represent a preferred type of starting material.

In yaddition to the general physical land chemical properties of the solvent extracts given yin Table IX, these starting materials may be further characterized b-y the tact that their average molecular Weight -is about 320 t0 600, the boiling point (initial) -is between 300 to 1000 F., the end boiling point is between 400 to l200 F., and they may exhibit pour points as high as 100 F. Chemically, the extracts may contain 2.0 to 4.5% Wt. of sulfur, exhibit a H/C Wt. ratio of 0.1-16 to 0.136, a H/C atom ratio of 1.383 to 1.622, a H/C atom ratio, based only on the aromatic portion, of 1.289 to 1.500, and the nearest empirical formula `is C22H30 to C44H66. The extracts may contain from about 15% to 50% by Weight of sulfur compounds, andl 30% to 90% by Weight of aromatic and thio compounds. Many of these characteristics, particularly the chemical characteristics, carry over into the polynuclear polybasicacids of this invention. In addition to the solvent extracts aforo-described, Ivarious solvent extracts and other sources now commercially available may be used as starting materials. This is illustrated by Table X showing an evaluation of some commercially available materials in preparing the complex acid products of this invention.

TABLE X Comparative Evaluatio'n of Available Aromatic Material 1n Polybaszc Aczd Production Percent Yield, g. Acid Extract Des1gnation Oil Acid/g. Number Reacted Na of Acid 5 05 77.2 11 2.7 153 14 4.3 251 14 3.0 191 14 5. 0 218 15 4.0 209 15 4.6 252 15 3.8 207 16 4.1 194 18 0.8 201 1s 4.2 V217 19 5.0 217 20 3.7 191 20 4.1 204 20 4.9 171 P 23 4.5 240 Solvent No. 4 14 4.5 241 Combined Reformate Polymers- 17 3.9 444 solvent Ext. No. 43 24 4. s 231 Solvent Ext. No. 44 26 5. 3 192 FOG Recycle Stock 28 4. 4 241 The reformate polymers consisted of a bottom 1% fractlon of reformate (95 octane numbers), had an API gravity of 10.3, and a distillatton range (corrected to 760 mm. Hg) as follows:

1Distillation was stopped at 600 F., leaving residue of 30%, no-loss basis.

The FCC recycle stock was a 19% extract (phenol solvent) of FCC recycle stock and had the following properties:

API 1.8 Percent sulfur 1.9 Bromine No 17 Refractive index (20 C.) 1.6372 Engler distillation:

IBP 589 F. 90% 745 F.

Without limiting the invention, the characteristics or the products of this invention are further disclosed as thus far evaluated. The novel diand polycarboxylic acids of this invention are mixtures, acids of the dihydronaphthalene, dihydrophenanthrene, and dihydroanthracene types averaging in molecular Weight from about 375 to 450, having several alkyl groups in each aromatic .nucleus wherein the sum of the carbon atoms in the alkyl substituents varies between 15 to 22. Despite the size of the acid molecules, the linkages through or between the carboxyl groups are about the same as those of phthalic and terephthalic acids. A portion of the aromatic rings or condensed aromatic rings is probably further condensed with naphthenic rings to form congurations similar to the steroid ring system. Extract dibasic acids from solvent extracts obtained in the production of bright stocks probably contain more highly condensed aromatic structures. Most of the sulfur (1.9 to 4.5% total sulfur being present) is in the form of heterocyclic rings with sulfur associated with both the aromatic type and naphthenio type structures present. Only trace amounts of the sulfur is present as highmolecular-weight aliphatic suldes. The nitrogen content of distilled solvent extracts is 0.01 to 0.04%. Analysis for the types of carbon linkages as percent Ca (carbon atoms in aromatic configuration), percent Cn (carbon atoms in naphthenic conguration), and percent Cp (carbon atoms in parainic configuration) gives results in the range of -40% Ca, '20-35% Cn and .3l-47% Cp, using the method of Kurty, King, Stout, Partikian and Skrabek, (Anal. Chem., 28 1928 (1956)). The polybasic acids of this invention have acid numbers (1948 method) Vof 160-500, MJ?. S0-90 C., Br. No. 16-24, sulfur 1.7-2.3%, are deep red in color, transparent in thin sheets, and contain 2-6% unsaponiiiables. They are soluble in ethyl ether, acetone, methyl ethyl ketone, tetrahydrofuran, benzene, toluene and xylene. The acids are useful in preparing resins including alkyds, polyesters, polyamides and epoxy resins.

Although the invention has been demonstrated by a number of examples, these are not to be construed as limiting. The term solvent extracts is used in its recognized meaning in the solvent extraction art. The term extract dibasic acids or extract polycarboxylic acids used herein shall be construed to include acids containing 2 or more carboxyl groups per molecule with the upper limit being about 4 or 5 carboxyl groups.

The hydrogenated, dewaxed, and clay-contacted Extract No. 44 (see Table III) had the following properties:

API 9.5 Color, NPA 7 Flash (COC), F. 420 Fire (COC), F. 465 Pour point, F. 5 Vis. (100 F.), sec. 1075 Vis. (210 R), sec. 58.5 Viscosity index (calc.) --96 Neut. No. (1948) 0.05 Sulfur, percent wt 2.60 Carbon residue, percent 0.01

The embodiments of the invention'in which an exclusive privilege or property is claimed are defined as follows:

1&6 1. The process of producing alkali metal adducts of aromatic compounds contained in a petroleum fraction of the group consisting of (l) Solvent extracts obtained in the solvent extraction of mineral lubricating oils with a slovent selective for aromatic compounds (2) hydrogenated, dewaxed and clay-contacted solvent extracts obtained in the solvent refining of mineral lubricating oils with a solvent selective for aromatic compounds and (3) FCC recycle stock boiling in the range of about K 589 F. to about 745 F.; said petroleum fraction also containing complex sulfurcontaining compounds which comprises mixing said petroleum fraction with an alkali metal at a temperature of above about 100 to 'about 190 C. to form a dispersion, maintaining said dispersion at said temperature for a time sufficient to start the reaction of said alkali metal with said petroleum fraction as indicated by a temperature rise of said dispersion, adding a reaction solvent of the group consisting of dimethyl ether, dimethyl glycol ether, tetrahydrofuran, methylal, dimethylformamide, trimethoxyethoxypropane,'formaldehyde and tetraethoxypropane to said dispersion and cooling the reaction mixture to a temperature of about 0 to 40 C.

2. The process in accordance with claim 1 in which said petroleum fraction comprises solvent extracts obtained in the solvent extraction of mineral lubricating oils using a solvent selective for aromatic compounds.

3. The process in accordance with claim 1 in which said solvent extracts are characterized by having an average molecular Weight of above about 300, contain an average of about 1.7 to 3.5 aromatic rings per mean aromatic molecule and contain about 1.9% to 4.5% by weight of sulfur.

4. The process in accordance with claim 1 in which said dispersion is cooled to said temperature of about 0 to 40 C. during the addition of said reaction solvent.

5. The process in accordance with claim 1 in which said mixing temperature is about 130 to 190 C., the time of mixing is about 2 to 10 minutes, the ratio of said petroleum fraction 'to alkali metal is about 6/1 to 26/1 and the 'ratio of said reaction solvent to said petroleum fraction is about 4/1 to 6/ 1.

6. The products produced by the process of claim 1.

7. The process of producing mixed mono, diand polycarboxylic acids from aromatic compounds contained in a petroleum fraction of the group consisting of 1) Solvent extracts obtained in the solvent extraction of mineral lubricating oils with a solvent selective for aromatic compounds (2) hydrogenated, dewaxed and clay-contacted solvent extracts obtained in the solvent reining of mineral lubricating oils with a solvent selective for aromatic compounds (3) FCC recycle stock boiling in the range of about 589 F. to about 745 F.

said petroleum fraction also containing complex sulfurcontaining compounds which comprises mixing said petroleum fraction with an alkali metal at a temperature of above about to about 190 C. to form a dispersion, maintaining said dispersion at said temperature for a time suflicient to start the reaction of said alkali metal with said petroleum fraction as indicated by a temperature rise of said dispersion, adding a reaction solvent of the group consisting of dimethyl ether, dimethyl glycol ether, tetrahydrofuran, methylal, dimethylformamide, trimethoxyethoxypropane, formaldehyde and tetraethoxypropane to said dispersion While cooling the dispersion to a temperature of about 0 to 40 C. to complete the formation of the adduct, further cooling the adduct reaction mixture to a temperature of about 5 to 100 C. in the presence of carbon dioxide to form the alkali metal salt of the corresponding carboxylic acids and acidifying said salt to ,form the free acids.

8. The process in accordance with claim 7 in which said petroleum fraction comprises solvent extracts obtained in the solvent extraction of mineral lubricating oils using a solvent selective for aromatic compounds.

9. The process in accordance with claim 8 in which said solvent extracts are characterized by having an average molecular Weight of above about 300, contain an average of about 1.7 to 3.5 aromatic rings per means aromatic molecule and contain about 1.9% to 4.5% by weight of sulfur.

10. The process in accordance with claim 7 in which the time of mixing is about 2 to 8 minutes, the ratio of said complex petroleum fraction to alkali metal is about 6/ 1 to 26/1 and the ratio of said reaction solvent to said petroleum fraction is about 4/1 to 6/ 1.

11. The process in accordance with claim 7 in which said carbonation is conducted by addition of Dry Ice.

References Cited in the le of this patent UNITED STATES PATENTS OTHER REFERENCES Conant et al.: 1. Am. Chem. Soc., vol. 50, pages 542-550 (1928).

Hansley: Ind. and Eng. Chem, vol. 43, pages 1759- 1766 (1951). (Available in Scientic Libra-ry.)

UNITED' STATES infr-Erfty I oFjlIcEv CERTIFIGATE` 0F i CRRECTON Patent No. 3, 153,087' October `13, 1964 Walter E. Kramer. etal.

It is hereby certified that error appears inthe above numbered patent requiring correction and that the, said Letters Patent should read as corrected below. l

Column 3, lines 14 and "-15, strike out; "-alakjli metal and aromatic hydrocarbon in combination with", column 7, TABLE V, B., in the heading, after "70 C," insert' a closing parenthesis; column ll, line l0, for. "sulfur," read sulfurcolumns ll and l2, TABLE VII Efxt. No. 2l, under "Percent C. R." for "08.6" read 0.86 same table, Ext. No. 44, underl Vis/1000i F." for "2.007" read "complex".

signed and sealed thisbaoth day. of April 1965.

(SEAL) Attest:

- EDWARD J. BRENNER Commissioner of Patents ERNEST W. SWIDER Attesting Officer 

1. THE PROCESS OF PRODUCING ALKALI METAL ADDUCTS OF AROMATIC COMPOUNDS CONTAINED IN A PETROLEUM FRACTION OF THE GROUP CONSISTING OF (1) SOLVENT EXTRACTS OBTAINED IN THE SOLVENT EXTRACTION OF MINERAL LUBRICATING OILS WITH A SOLVENT SELECTED FOR AROMATIC COMPOUNDS (2) HYDROGENATED, DEWAXED AND CLAY-CONTACTED SOLVENT EXTRACTS OBTAINED IN THE SOLVENT REFINING OF MINERAL LUBRICATING OILS WITH A SOLVENT SELECTED FRO AROMATIC COMPOUNDS AND (3) FCC RECYCLE STOCK BOILING IN THE RANGE OF ABOUT 589*F. TO ABOUT 745*F., SAID PETROLEUM FRACTION ALSO CONTAINING COMPLEX SULFURCONTAINING COMPOUNDS WHICH COMPRISES MIXING SAID PETROLEUM FRACTION WITH AN ALKALI METAL AT A TEMPERATURE OF ABOVE ABOUT 100* TO ABOUT 190*C. TO FORM A DISPERSION, MAINTAINING SAID DISPERSION AT SAID TEMPERATURE FOR A TIME, SUFFICIENT TO START THE REACTION OF SAID ALKALI METAL WITH SAID PETEROLEUM FRACTION AS INDICATED BY A TEMPERATURE RISE OF SAID DISPERSION, ADDING A REACTION SOLVENT OF THE GROUP CONSISTING OF DIMETHYL ETHER, DIMETHYL, GLYCOL ETHER, TETRAHYDROFURAN, METHYLAL, DIMETHYLFORMAMIDE, TRIMETHOXYETHOXYPROPANE, FORMALDEHYDE AND TETRAETHOXYPROPANE TO SAID DISPERSION AND COOLING THE REACTION MIXTURE A TEMPERATURE OF ABOUT 0* TO 40*C.
 6. THE PRODUCTS PRODUCED BY THE PROCESS OF CLAIM
 1. 7. THE PROCESS OF PRODUCING MIXED MONO-, DI- AND POLYCARBOXYLIC ACIDS FROM AROMATIC COMPOUNDS CONTAINED IN A PETROLEUM FRACTION OF THE GROUP CONSISTING OF (1) SOLVENT EXTRACTS OBTAINED IN THE SOLVENT EXTRACTION OF MINERAL LUBRICATING OILS WITH A SOLVENT SELECTIVE FOR AROMATIC COMPOUNDS (2) HYDROGENATED, DEWAXED AND CLAY-CONTACTED SOLVENT EXTRACTS OBTAINED IN THE SOLVENT REFINING OF MINERAL LUBRICATING OILS WITH A SOLVENT SELECTIVE FOR AROMATIC COMPOUNDS (3) FCC RECYCLE STOCK BOILING IN THE RANGE OF ABOUT 589*F. TO ABOUT 145*F. SAID PETROLEUM FRACTION ALSO CONTAINING COMPLEX SULFURCONTAINING COMPOUNDS WHICH COMPRISES MIXING SAID PETROLEUM FRACTION WITH AN ALKALI METAL AT A TEMPERATURE OF ABOUT ABOUT 100* TO ABOUT 190*C. TO FORM A DISPERSION, MAINTAINING SAID DISPERSION AT SAID TEMPERATURE FOR A TIME SUFFICIENT TO START THE REACTION OF SAID ALKALI METAL WITH SAID PETROLEUM FRACTION AS INDICATED BY A TEMPERATURE RISE OF SAID DISPERSION, ADDING A REACTION SOLVENT OF THE GROUP CONSISTING OF DIMETHYL ETHER, DIMETHYL GLYCOL EHTER, TETRAHYDROFURAN, METHYLAL, DIMETHYLFORMAMIDE, TRIMETHOXYETHOXYPROPANE, FORMALDEHYDE AND TETRAETHOXYPROPANE TO SAID DISPERSION WHILE COOLING THE DISPERSION TO A TEMPERATURE OF ABOUT 0* TO 40*C. TO COMPLETE THE FORMATION OF THE ADDUCT, FURTHER COOLING THE ADDUCT REACTION MIXTURE TO A TEMPERATURE OF ABOUT -5* TO -100*C. IN THE PRESENCE OF CARBON DIOXIDE TO FORM THE ALKALI METAL SALT OF THE CORRESPONDING CARBOXYLIC ACIDS AND ACIDIFYING SAID SALT TO FORM THE FREE ACIDS. 